September 13, 2015 defense-aerospace.com (Source: Deutsche Welle German radio)

A group monitoring the conflict in Syria says Russian forces are expanding a major airport in Latakia province. Russia has reiterated its support for the Syrian regime, but denies it is staging a military build-up.

The Britain-based Syrian Observatory for Human Rights said on Sunday that Russian forces were working to extend an airstrip near a military airport in Latakia province, a stronghold of Syrian President Bashar al-Assad and his minority Alawite sect.

"Russian forces are building a long runway capable of accommodating large aircraft near the Hemeimeem military airport in Latakia province," the Observatory said, adding that hundreds of Russian technicians and military advisers had been brought to the site.

It also reported that the Russians were "preventing Syrians, whether military or civilian, from entering the area where they are building the runway."

The Hemeimeem airport, which houses a military base, is the second most important government-controlled airport after Damascus airport. It has come under shelling from rebel militants as they advance through the region.

The Observatory's director, Rami Abdurrahman, said sources had also reported that Russia was extending the Hamadiyeh airport in Tartus province, another regime stronghold, where Russia has a naval facility (photo above).

The Observatory bases its reports on a network of civilian, military and medical sources inside Syria.

Washington's fears

The claims come as US officials increasingly voice concerns that Russia is stepping up its military activities within the country, with President Barack Obama warning Moscow against propping up Assad. Washington says Russian aid is helping Assad avoid negotiating a political solution to the conflict.

Moscow, a long-time Assad ally, has freely admitted its support for the Syrian government, but denies any claims of a military build-up in the country, saying it is simply taking part in international efforts to combat the jihadist group "Islamic State" ("IS), which has made large territorial gains in both Syria and Iraq.

Continued Russian help

On Sunday, Russian Foreign Minister Sergei Lavrov said Russia would continue to back Assad's regime in "its efforts to fight terrorism."

He also criticized the West for refusing to cooperate with Syrian forces in the fight against "IS," calling the government armed forces "the most efficient military force in the country."

Syria has been embroiled for more than four years in a civil conflict that began with anti-government protests in March 2011. More than 250,000 people have been killed in the violence, which has seen the government lose considerable swathes of territory to rebels and various jihadist groups such as "IS."